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Title (Primary) Characterization of hexachlorocyclohexane isomer dehydrochlorination by LinA1 and LinA2 using multi-element compound-specific stable isotope analysis
Author Liu, Y.; Fu, J.; Wu, L.; Kümmel, S.; Nijenhuis, I.; Richnow, H.H.
Journal Environmental Science & Technology
Year 2022
Department ISOBIO
Volume 56
Issue 23
Page From 16848
Page To 16856
Language englisch
Topic T7 Bioeconomy
Supplements https://pubs.acs.org/doi/suppl/10.1021/acs.est.2c05334/suppl_file/es2c05334_si_001.pdf
Keywords transformation; isotope fractionation; pesticides; LinA enzymes; dehydrochlorination
Abstract

Dehydrochlorination is one of the main (thus far discovered) processes for aerobic microbial transformation of hexachlorocyclohexane (HCH) which is mainly catalyzed by LinA enzymes. In order to gain a better understanding of the reaction mechanisms, multi-element compound-specific stable isotope analysis was applied for evaluating α- and γ-HCH transformations catalyzed by LinA1 and LinA2 enzymes. The isotopic fractionation (εE) values for particular elements of (+)α-HCH (εC = −10.8 ± 1.0‰, εCl = −4.2 ± 0.5‰, εH = −154 ± 16‰) were distinct from the values for (−)α-HCH (εC = −4.1 ± 0.7‰, εCl = −1.6 ± 0.2‰, εH = −68 ± 10‰), whereas the dual-isotope fractionation patterns were almost identical for both enantiomers (ΛC–Cl = 2.4 ± 0.4 and 2.5 ± 0.2, ΛH–C = 12.9 ± 2.4 and 14.9 ± 1.1). The εE of γ-HCH transformation by LinA1 and LinA2 were −7.8 ± 1.0‰ and −7.5 ± 0.8‰ (εC), −2.7 ± 0.3‰ and −2.5 ± 0.4‰ (εCl), −170 ± 25‰ and −150 ± 13‰ (εH), respectively. Similar ΛC–Cl values (2.7 ± 0.2 and 2.9 ± 0.2) were observed as well as similar ΛH–C values (20.1 ± 2.0 and 18.4 ± 1.9), indicating a similar reaction mechanism by both enzymes during γ-HCH transformation. This is the first data set on 3D isotope fractionation of α- and γ-HCH enzymatic dehydrochlorination, which gave a more precise characterization of the bond cleavages, highlighting the potential of multi-element compound-specific stable isotope analysis to characterize different transformation processes (e.g., dehydrochlorination and reductive dehalogenation).

Persistent UFZ Identifier https://www.ufz.de/index.php?en=20939&ufzPublicationIdentifier=26889
Liu, Y., Fu, J., Wu, L., Kümmel, S., Nijenhuis, I., Richnow, H.H. (2022):
Characterization of hexachlorocyclohexane isomer dehydrochlorination by LinA1 and LinA2 using multi-element compound-specific stable isotope analysis
Environ. Sci. Technol. 56 (23), 16848 - 16856